The present invention relates generally to shaft couplings and more particularly to a shaft coupling for transmitting a torque force from one shaft to another.
The problem of how to couple one shaft to another for transmitting a torque force is a longstanding one. This has particularly been a problem in the farming community wherein the power take-off of an agricultural tractor frequently needs to be connected and disconnected to utilize one implement and then another. This problem has been solved in the past in one degree or another, and one of the most commercially successful of these solutions is a connection of the type disclosed in U.S. Pat. No. 2,448,278 to Ronning which was patented in 1948.
In U.S. Pat. No. 2,448,278, a pin is biased to one position within a housing so that it will contact one spline of a power take-off to thereby hold the coupling together. In another position of the pin, it is moved so that it does not block or contact any of the splines and thereby allows the housing to be removed from the power take-off shaft.
Another type of coupling device particularly for use with agricultural equipment is shown in U.S. Pat. Nos. 3,969,033, 3,992,119 and 3,992,120 issued to Recker. These patents disclose a design for locking on all of the splines of a power take-off shaft by use of a rotatable splined and grooved sleeve disposed within a coupler housing. The locking mechanism is biased to a locked position.
Still another example of a type of coupling structure for selectively coupling splined shafts together is shown in U.S. Pat. No. 3,260,541 to Sadler et al, which patent discloses a plurality of balls in a housing which are selectively movable into and out of locking engagement with a power take-off shaft. The balls are biased to locked position.
In all of the above mentioned patents, the devices disclosed require that before the power take-off coupler is connected to the power take-off shaft that the locking mechanism be manually moved to an unlocked position. Then once the coupler is properly positioned on the shaft, the locking mechanism will automatically move to a locked position. To uncouple the shaft, the locking mechanism is manually moved to an unlocked position and the coupler is slid off of the shaft.
It would be very desirable to be able to have such coupling devices of the type referred to above, for example, automatically moved to and held in an unlocked position when the power take-off coupler is removed so that such coupler mechanism could receive the shaft again when re-coupling is desired without the need to manually move or reset the locking mechanism, while still including the feature that the locking mechanism will automatically move to the shaft locking position once the coupler is again connected or pulled on the shaft to the proper position thereof with respect to the coupler mechanism.